Photos from the Mars Reconnaissance Orbiter taken since the start of the mission showed evidence of water flow, but the NASA scientists were very reticent to attribute it to actual liquid water. Using a spectrometer on the MRO they have now proven that the flow is briny water, still liquid at temperatures as low as -23 °c because of the concentration of salts in the mixture reducing the freezing point.

The truth may be puzzling. It may take some work to grapple with. It may be counterintuitive. It may contradict deeply held prejudices. It may not be consonant with what we desperately want to be true. But our preferences do not determine what's true. -Sagan

Neat design, hard to read even with the zoom, but after all, they are trying to sell posters. I wish it really was all of humankind's spaceprobes.

It might not be all of humankind's spaceprobes but it's definitely more than just NASA's. Most of the Venusian probes were Soviet; starting from the bottom left I see many of the Venera probes are pictured, as well as the Japanese IKAROS. Among the pictured lunar probes I see the Soviet Luna probes and the Lunokhod rover, the Japanese SELENE, the Chinese Chang'e and the Indian Chandrayaan. I can see some of the European probes, like Huygens (which went to Titan) and Rosetta & Philae (studying Comet "67P/Churyumov-Gerasimenko").